O'Keefe U.S. Pat. No. 3,995,371 describes an electroless plating method for applying a thin continuous layer of a metal such as silver upon a tooth surface. The purpose is to seal that surface with a highly adherent layer of metal, thereby providing a more effective substrate for amalgam and other dental restorative materials.
The patented procedure involves the steps of etching an enamel surface and then coating that surface with a plating mixture containing a water soluble metal salt (such as silver nitrate or silver fluoride) and a reducing agent for the metal ions of that salt. The plating mixture is maintained in contact with the enamel surface for several minutes until a continuous shiny layer of metallic silver is deposited on that surface.
Unfortunately, the patented process has a significant limitation. As acknowledged by the patentee (column 6, line 63, to column 7, line 13), the process is effective only for coating enamel; it is not effective for coating predentin (dentin) which, in contrast to enamel, has a large proportion of organic matter. Where a dental excavation extends through the enamel of a tooth into the dentin, a common situation, the patented process can be used only to provide a continuous metallic coating about the edges or rim of the excavation.
The significance of that shortcoming becomes apparent when it is considered that one major advantage of the patented procedure is to provide a secure attachment for an amalgam restoration without the extensive undercutting commonly required within an excavation in order to obtain secure mechanical attachment of the amalgam filling. In those cases where the excavation exposes a substantial area of dentin, the dentist must proceed to enlarge the excavation, providing undercut recesses in the conventional manner, in order to insure secure attachment of the filling.
For the same reasons, the patented process would appear inapplicable in certain prosthodontic procedures such as overdenture preparation. For example, if an endodontically treated tooth is severed at the gum line with the root remaining in place to provide support for a denture and to prevent resorption of bone that might otherwise occur if the root were removed, the patent disclosure makes it clear that some other process must be used to seal the exposed surface of the tooth since no appreciable enamel areas would remain, such surface consisting almost entirely of dentin.